The helianthemum (also known as Rock rose) is a vastly popular alpine sub-shrub, of which there are many named cultivars. They grow to about 15-30cm/6-l2in high, with a spread of 30-60cm/12-24in. Helianthemum ‘Jubilee’ has a mass of double pale yellow flowers, about 2.5cm/1 in across, held in terminal clusters, in early and midsummer. The leaves are small, elliptical in shape, dark green above and grey-green below.
Cultivation and propagation
Plant helianthemum in early fall or early spring in any well drained soil and in full sun. You will get a second flush of flowers if the plants are trimmed over in midsummer.
At the end of flowering, cut the stems back hard, or the shrub becomes straggly, flowers less freely and is shorter lived. Take short cuttings with a heel after the first flowering, and put in a cold frame to root. This is a hardy plant. This plant is likely to need clipping. Helianthemum is good for chalky/sandy soil.
A good plant to tumble over a low wall, or in company with other alpines in a raised bed, or even holes in paving or a dry wall.
H. Wisley Primrose’ (single, with grey-green leaves); H. ‘Raspberry Ripple’ (white flower with red centers).